It is repeatedly claimed that the dumping of nuclear waste poses no threat to people living nearby.
Background
Officials repeatedly claim nuclear waste dumping poses no threat to nearby populations. If that claim were certain, there would be no reason to avoid densely populated areas.
Conclusion
Since waste is dumped only in sparsely populated areas, those responsible must have some misgivings about safety.
Evidence
The choice to avoid densely populated areas is treated as evidence of safety doubts.
Evaluate
The argument assumes the only reason to put dumps in sparsely populated areas is safety concern. But that is not the only possible reason. If sparsely populated areas are simply easier or cheaper to use — for non-safety reasons — then the policy choice does not imply doubts about safety at all.
Goal
The correct answer should give a non-safety reason to prefer sparsely populated areas, breaking the inference from "they avoid populated areas" to "they have safety doubts."